Epoxy resins are widely used as thermoset polymers for manufacturing fibre reinforced composites in structural applications. The highly crosslinked structure of these materials makes them inherently brittle and susceptible to microcrack formation deep within the structure where detection and intervention are difficult or impossible.
The development of self healing or mendable epoxy resins has been proposed in recent years to restore strength to damaged components and make these materials safer to use, more reliable, and easier to maintain. The mendable epoxy resins have typically contained a dispersion of brittle vessels containing liquid healing agents that are capable of fracturing to release healing agents which subsequently rejoin contiguous damaged areas. These known technologies possess a number of limitations such as high raw materials cost, limited stability of the healing agents, extra processing steps required for encapsulating or infiltration of the healing agents into the delivery vessels, and limited ability to heal multiple incidents of damage.
An alternative approach has involved using thermoplastic healing agents. Thermoplastic healing agents have been included as additives or directly blended with the matrix to form smart epoxy-carbon fibre laminate structures exhibiting structural health monitoring and self-healing functions whereby the carbon fibres act as sensing elements to detect potential damages, by monitoring change in resistance, and as local heating elements to trigger the healing process.
Presently known thermoplastic based mendable polymers are limited by the need for high temperatures and pressures during healing, or achieving healing at the expense of reduced strength.
A need exists for new and alternative polymers and polymer materials that can provide improved self healing characteristics.